In recent years, the importance of support for quality standards such as ISO has been increased and the need for high-quality welding is getting higher, a flexible welding system capable of supporting small lot multi-production required by diversified customer needs, e.g. in the automotive industries.
In order to assure the improvement of welding quality, a welding power supply capable of performing stable wide-range welding from a low current area to a high current area, which is from 30 A to 350 A, has been developed. A wire feeder equipped with an encoder is employed to increase the stability of welding in the low current area. A robot controller and a welding power supply are integrated to dramatically reduce the footprint. These efforts has provided speedy installation and system startup as well as flexible system deployment (for example, refer to Takuji Hayashi, “Development of Robot Equipped with Full Digital Welding Power Supply” disclosed in “Welding Engineering” (Japan Welding Engineering Society) Vol. 51, No. 1, page 72 (2003).
FIG. 3 shows a general configuration of a conventional arc-welding robot.
Referring to FIG. 3, a robot main body 101 connects to a robot controller 102 via a robot drive power cable 102a for driving the robot and a robot control cable 102b for position control of the robot.
The robot controller 102 connects to a welding power supply 103 via an interface cable (not shown). The robot controller 102 and the welding power supply 103 are connected in a housing to form an integral shape.
To the robot main body 102 are attached a welding torch 104 and a wire feeder 105 for feeding welding wire to the welding torch 104.
FIG. 4 is a detailed explanatory drawing of the vicinity of the wire feeder 105.
Between the robot main body 101 and the welding power supply 103 is connected a welding control cable 103a. Inside the welding control cable 103a are accommodated a power cable 105b for driving a wire feeder motor 105a and gas valve control cable 105d for a gas valve 105c and a power voltage feedback cable 105e. 
Between the wire feeder 105 and the welding power supply 103 is connected a feeder sensor cable 103b for stabilizing the wire feed amount to a wire feeder encoder 105f in order to monitor the wire feed speed.
Gas required for welding is supplied from a gas bomb 106 to a welding torch 104 via a gas flow regulator 107, a gas hose 108, a hose (not shown) in the robot main body 101 as well as a gas hose 105g and a gas valve 105c. 